Determining Amount
of Cushioning Required

Gemstar strives to provide
exceptional protection for your
equipment inside and outside of
your case. To this end, we create
custom foam sets based on your
unique needs.

Fragility of the Item

The so-called "educated guess" of the G factor for a given item can be dangerous for two reasons. First, if the guess is too low, the package may be over-designed resulting in higher package costs than necessary. Second, if the G factor is too high, an under-designed package will be developed and high damage claims are likely. Unfortunately, the degree of fragility for most products has never been determined, or it is not generally known. However, with the advent of ultra-sensitive electronic testing equipment, it has become necessary to determine fragility factors. The table to the right may be used as a guide where the G factor of a product is known, but it should never be considered a substitute for test information on a specific product.
Extremely Fragile 15 - 25 Gs
Special military applications, precision aligned test instruments
Very Delicate 25 - 40 Gs
Mechanically shock mounted instruments and electronic equipment (shock mounts should be firmly secured prior to packaging. They are provided for in-service protection only.)
Delicate 40 - 60 Gs
Aircraft accessories, computer equipment and other electrically operated office equipment
Moderately Delicate 60 - 85 Gs
Video equipment, computer monitors, aircraft accessories
Moderately Rugged 85 - 115 Gs
Equipment with minimal electronic controls
Rugged 115 Gs +
Machinery
Handling of the Item

The anticipated height of drop, based on potential hazards that might be encountered during shipping and handling, must also be determined. A line between "normal handling" and "rough handling" must be drawn. A heavy item may not be dropped higher than 12 to 18 inches during normal handling, but during rough handling, such as falling from the back of a truck, a drop height of 42" may be encountered. If an item is lightweight and could be thrown by baggage handler, a drop height of 36" is realistic. A guide for estimating anticipated drop heights is below.
Weight Range
Gross Weight
in Pounds		 Type of Handling Drop Height in
Inches
0 - 20
21 - 50
51 - 250
251 - 500
501 - 1000
1001 - up 		1 person throwing
1 person carrying
2 person carrying
Light equipment handling
Light equipment handling
Heavy equipment handling 		42
36
30
24
18
12




Step 1:

  • Determine foam load. Divide the item weight, in pounds, by the square inches of the surface that will rest on the foam. This will establish the foam loading in lb/sq. in. for one side. (This must be calculated for each of the six sides of a rectangular item).

Step 2:

  • Determine what type and density foam is to be used. For foam loading:


    0.1 to 0.3 lb/sq in. use 2 lb/cubic ft. polyurethane
    0.4 to 0.6 lb/sq in. use 4 lb/cubic ft. polyurethane
    0.7 to 1.0 lb/sq in. use 2 lb/cubic ft. polyethylene

Step 3:

  • Determine the fragility factor in “G” from the Fragility of the Item table. This is the most critical factor in determining the correct protection and lowest cost for packaging your product.

Step 4:

  • Determine drop height in inches from the Handling of the Item table.

Step 5:

  • Select the proper material graph and enter at the fragility factor in “G”, proceed horizontally to intersect the curve at the drop height in inches and then move vertically down from this point of intersection to the indicated foam thickness required in inches.

Step 6:

  • Determine the case size by using the chart below.
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